A TORY Cabinet minister has confessed to having an affair amid claims he was being blackmailed by a Tory aide.

Robert Halfon, who sits at Cabinet meetings as a minister without portfolio and is deputy chairman of the Conservative Party, has said he is "ashamed" after admitting to cheating on his partner.

It follows reports the 46-year-old had a six-month fling with a young party activist behind his long-term partner's back.

The Mail on Sunday claimed Tory election aide Mark Clarke had been trying to blackmail Mr Halfon over the affair, after allegedly attempting to obtain photos of the minister and the woman leaving a posh London gentleman's club.